A Novel Fluorine Relaxation Switch for Tracking the Binding & Intracellular Processing of Molecularly Targeted Nanoparticle Contrast Agents

Lingzhi Hu¹, Junjie Chen¹, Shelton D. Caruthers¹, Gregory M. Lanza¹, Samuel A. Wickline¹

In the field of molecular imaging with nanoparticle contrast agents, it would be advantageous to know not only that a particle binds to its target but also that it is internalized and subsequently processed and sorted to the subcellular compartment.Here we develop an analytical description and experimental validation of 19F longitudinal T1 relaxation as an indicator for assessing the integrity of paramagnetic PFC NP. When Gd is stripped from the nanoparticle surface, a relaxation switch occurs revealing the transition from intact bound particle to processed constituents.